LibC: Add endian.h

This is part of POSIX issue 2024 and some software depends on it

userspace/libraries/LibC/endian.cpp

@@ -0,0 +1,31 @@
+#include <BAN/Endianness.h>
+
+#include <endian.h>
+
+#define BE_TO_H(size) \
+	uint##size##_t be##size##toh(uint##size##_t x) { return BAN::big_endian_to_host(x); }
+BE_TO_H(16)
+BE_TO_H(32)
+BE_TO_H(64)
+#undef BE_TO_H
+
+#define H_TO_BE(size) \
+	uint##size##_t htobe##size(uint##size##_t x) { return BAN::host_to_big_endian(x); }
+H_TO_BE(16)
+H_TO_BE(32)
+H_TO_BE(64)
+#undef H_TO_BE
+
+#define LE_TO_H(size) \
+	uint##size##_t le##size##toh(uint##size##_t x) { return BAN::little_endian_to_host(x); }
+LE_TO_H(16)
+LE_TO_H(32)
+LE_TO_H(64)
+#undef LE_TO_H
+
+#define H_TO_LE(size) \
+	uint##size##_t htole##size(uint##size##_t x) { return BAN::host_to_little_endian(x); }
+H_TO_LE(16)
+H_TO_LE(32)
+H_TO_LE(64)
+#undef H_TO_LE